One of the leading causes of death worldwide is coronary heart disease. It is commonly instigated by atherosclerosis, which is the deposition of plaque on arterial vessel walls. Such deposition can result in a narrowing (stenosis) of arteries, obstructed and reduced blood flow, and increased risk of heart attack. Angioplasty, a routine surgical procedure, can be performed to widen stenotic arteries. Although successful, angioplasty can suffer from non-uniform arterial widening and re-narrowing (restenosis) due to post-surgical recoil of the artery. To mitigate these shortcomings, stenting can be used as an alternative to angioplasty in suitable candidates.
Stents are expandable meshed cylindrical scaffolds which can be constructed from medical grade stainless steel. They can vary in size from 9 to 23 mm in length, and from 2.5 to 4.0 mm in diameter. Stents can be implanted within the lumen of stenotic arterial vessels in order to widen them and reduce the effects of atherosclerosis. These devices can be implanted as bare metal stents (BMS), or coated with a polymer drug delivery system in drug eluting stents (DES). Despite the advantages of BMS over angioplasty, their function can be limited by complications associated with biocompatibility. For example, post-stent restenosis due to neointimal hyperplasia (cellular hypertrophy, proliferation and deposition of extracellular matrix on the stent and around the site of implantation) remains a difficult challenge.
To combat neointimal hyperplasia (NH), DES employ a polymeric coating that releases anti-proliferative medications. However, concerns regarding delayed healing, late stage thrombosis and hypersensitivity to the polymeric resin continue to surround DES. In light of the challenges that both BMS and DES face, further research into alternative strategies for the reduction of both NH and physiological attack of the stent surface is warranted.